1. Field of the Invention
The present invention relates generally to the treatment of arterial or vascular disease at the intersection of two or more arteries or blood flow passageways, including, for example, abdominal aortic aneurysms or occlusive disease, and more particularly to a method and structure for treatment of abdominal aortic aneurysms with little or no aortic neck length below at least one of the renal arteries.
2. Description of the Related Art
In the prior art, treatment of arterial disease at the intersection of two or more arteries or blood flow passageways, such as, for example, abdominal aortic aneurysms or aortic occlusive disease, was effected by various surgical techniques, some of which involved the use of stent-grafts. The use of stent-grafts provided methods that were the least invasive and therefore involved less risk of infection and adverse patient reaction. However, use of prior art stent-graft structures typically required a minimum length of healthy tissue distance, or neck, between the the diseased portion of the artery, (such as the abdominal aortic aneurysm), and branch arteries (e.g., the renal arteries). This minimal neck length was specified to increase the possibility of a good seal between the prior art stent-graft structure and the wall of the major artery (e.g., the aorta) while at the same time allowing blood to flow to the intersecting branch arteries (e.g., the renal arteries). Typically, a neck length of approximately one and one-half centimeters was specified to use most prior art structures.
Unfortunately, many arterial diseases extended to closely approach or include the intersection of branching arteries or blood flow passageways, which diminishes or eliminates the available neck length, so they were untreatable or had to be treated by more invasive procedures (i.e., open surgery). However, the more invasive procedures, such as surgery, required that the patient be strong enough to survive the procedure, otherwise, treatment was postponed and/or withheld. Consequently, previously, many arterial diseases and aneurysms had to be either treated by more intrusive, and potentially dangerous, methods or, in some cases, the patient would simply have to wait until he or she was strong enough to potentially survive the surgery. Postponing or withholding treatment could result in a rupture of the arterial wall, and heavy hemorrhaging that often proves fatal. Consequently, waiting for treatment, or withholding treatment is not a desirable option.
To avoid more invasive surgery, or if surgery was not a viable option, doctors would consider using other prior art methods and structures in cases where the neck length was smaller than the specified minimum.
One prior method to address the situation where arterial disease occurred at the location of a branch arteries and where there was little or no arterial neck length between the diseased portion and the closest intersecting branch was to make a custom structure that would span the aneurysm and intersecting branch arteries (e.g., the renal arteries) and would thereby form a seal between the stent-graft and healthy tissue on the walls of the major artery (e.g., the aorta) above the aneurysm and intersecting branch arteries. However, in order to use this type of structure, fenestrations had to be custom made in the stent-graft to allow passage of blood to the intersecting branch arteries (e.g., the renal arteries).
In one prior art example, the procedure included placing a stent graft across the intersection of the aorta and the renal arteries. Preformed openings in the stent graft corresponds to the locations of the two branching renal arteries. Two secondary stent-grafts are then delivered and positioned in the side branches. This method required first precisely measuring, through imaging techniques, the exact location of the branch of the two renal arteries. To effectively use this method, the size or diameter of the two renal artery branches needed to be precisely measured and the lateral openings of the main graft and the open ends of the branch grafts had to be precisely sized so that once they were deployed and positioned in the respective main and branch arteries, they would fit to seal the aneurysm. Using this method, the main and branch stented grafts were then coupled to each other with a system of grooves and flanges or ribs, the grooves of one being received in the flange of the other to lock them together.
As discussed above, the prior art “solutions” to the little or no neck problem required a customized stent-graft structure having precisely measured and implemented features such as the longitudinal distance between branches, the radial positioning of the openings, and diameters of the openings. Consequently, the custom stent-grafts used with prior art techniques were not easily adaptable to mass production.
Because the custom made stent-grafts used with prior art techniques were custom made, there was considerable time lag between diagnosis and deployment of the stent-graft while waiting for the custom made stent-graft to be built. Since the aorta and renal arteries are comprised of living tissue, their physical dimensions, so critical to prior art methods, could change between when the measurements were taken and when the stent was deployed.
Custom stent-grafts used with the prior art required precise measurement and production techniques, were vulnerable to error, had to be special ordered well in advance of their use, and could not accommodate minor changes in the patient's physiology.
What is needed is a method and apparatus for treating arterial disease that can be more flexibly applied and can be used on short notice in a variety of situations and on a variety of anatomies.